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All organisms need energy to live. Energy is obtained from food. Green plants are the only organisms that can capture energy from sunlight and make their own food. In this lesson we are going to talk about Food Chains and Food Webs in the environment. Try Food Chains Quiz 1 and Food Chains Quiz 2 at the end of the lesson to check your knowledge.

Producers of a food chain

A green plant should always be the first link of a food chain. Green plants are the only organisms that can directly get the sun's energy and make their own food through a process called photosynthesis.

What are herbivores?

Herbivores are animals that only feed on plants.

What are omnivores?

Omnivores are animals that eat a variety of food of both plant and animal origin.

Carnivores and Top Predators

Carnivores are animals that only feed on other animals. These are also known as the top predators as they are at the highest point of the food chain. Top predators have a little or no enemies. They usually consume all lower levels and are not consumed by any other animals until they die. Lions, tigers, crocodiles, eagles are the best examples for top predators.

Some other examples of top predators

Prey is an animal that a predator feeds on. For example, a lion feeds on a zebra. So, the zebra is the prey of the lion.

All animals depend on plants directly or indirectly for food and energy.

Primary Consumers

Primary consumers are the second link of a food chain. They are usually herbivores that eat green plants or sometime that eat both plants and animals.

The green plants are the food of all herbivores that are primary consumers.

Secondary Consumers

Secondary consumers are the third link of a food chain. They can be either omnivores or carnivores.

The herbivores are the food for carnivores that are secondary, tertiary or quaternary consumers.

Tertiary and Quaternary Consumers

Tertiary consumers are the fourth link of a food chain while quaternary consumers are the fifth link of a food chain. They are usually the carnivores that are top predators.

Secondary consumers are the food for carnivores or top predators that are tertiary or quaternary consumers.

Sometimes tertiary consumers can be the food for quaternary consumers.

Likewise, step by step, the energy in food flows from the producers to consumers.

Scavengers and decomposers

When an organism dies, it is eventually eaten by scavengers like crows, vultures, ants, worms and crabs and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues in the environment.

Crows, vultures and hyenas are the best examples of vertebrate scavengers while ants are good invertebrate scavengers in the environment. They eat dead bodies of animals and plants.

Bacteria, fungi, algae, lichens are the examples of decomposers. They break down dead bodies of plants and animals and let the essential nutrients in the dead matter mix with the ecosystem again, so that no waste would pile up.

A food chain is a flow of energy from a green plant (producer) to an animal (consumer) and to another animal (another consumer) and so on.

What does a food chain show us?

1) A food chain shows us a series of living things that depend on each other for food energy.

2) A food chain shows us the relationship between the animals and plants in a habitat.

3) A food chain shows us the way energy flows through a habitat.

What are the features of a food chain?

1) There are usually three or four organisms in a food chain:

Each of these organisms in a food chain is called a link. These links make a food chain.

2) Food chains usually start with a producer or a green plant :

This is the link where energy from the sun enters the food chain.

Food Chains

In nature the food chains are not as direct as we've seen them in our discussion. The food chains are highly cross linked (connected) and highly complicated. In any habitat there may be many kinds of animals that feed on the same plants and there may be many predators that feed on the same kinds of prey. Therefore there will be several food chains in any habitat. These food chains are inter-linked and they form food networks in the habitat.

What is a food web?

A type of a food network with several inter-linked food chains in a habitat is called a food web.

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Food Chains and Food Webs | Examples of Food Chains and Food Webs

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All organisms need energy to live. Energy is obtained from food. Green plants are the only organisms that can capture energy from sunlight and make their own food. In this lesson we are going to talk about Food Chains and Food Webs in the environment.

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Kids learn about the food chain and food web. How energy cycles and transfers through living organisms.

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The food chain describes who eats whom in the wild. Every living thing-from one-celled algae to giant blue whales ( Balaenoptera musculus)-needs food to survive. Each food chain is a possible pathway that energy and nutrients can follow through the ecosystem.

For example, grass produces its own food from sunlight. A rabbit eats the grass. A fox eats the rabbit. When the fox dies, bacteria break down its body, returning it to the soil where it provides nutrients for plants like grass.

Of course, many different animals eat grass, and rabbits can eat other plants besides grass. Foxes, in turn, can eat many types of animals and plants. Each of these living things can be a part of multiple food chains. All of the interconnected and overlapping food chains in an ecosystem make up a food web.

Organisms in food chains are grouped into categories called trophic levels. Roughly speaking, these levels are divided into producers (first trophic level), consumers (second, third, and fourth trophic levels), and decomposers.

Producers, also known as autotrophs, make their own food. They make up the first level of every food chain. Autotrophs are usually plants or one-celled organisms. Nearly all autotrophs use a process called photosynthesis to create "food" (a nutrient called glucose) from sunlight, carbon dioxide, and water. Trophic Levels

Plants are the most familiar type of autotroph, but there are many other kinds. Algae, whose larger forms are known as seaweed, are autotrophic. Phytoplankton, tiny organisms that live in the ocean, are also autotrophs. Some types of bacteria are autotrophs. For example, bacteria living in active volcanoes use sulfur compounds to produce their own food. This process is called chemosynthesis.

The second trophic level consists of organisms that eat the producers. These are called primary consumers, or herbivores. Deer, turtles, and many types of birds are herbivores. Secondary consumers eat the herbivores. Tertiary consumers eat the secondary consumers. There may be more levels of consumers before a chain finally reaches its top predator. Top predators, also called apex predators, eat other consumers.

Higher-level consumers (i.e., secondary, tertiary, and above) can be carnivores (animals that eat other animals) or omnivores (animals that eat both plants and animals). Omnivores, like people, consume many types of foods. People eat plants, such as vegetables and fruits. We also eat animals and animal products, such as meat, milk, and eggs. We eat fungi, such as mushrooms. We also eat algae, in edible seaweeds like nori (used to wrap sushi rolls) and sea lettuce (used in salads).

Detritivores and decomposers are the final part of food chains. Detritivores are organisms that eat nonliving plant and animal remains. For example, scavengers such as vultures eat dead animals. Dung beetles eat animal feces.

Decomposers like fungi and bacteria complete the food chain. They turn organic wastes, such as decaying plants, into inorganic materials, such as nutrient-rich soil. Decomposers complete the cycle of life, returning nutrients to the soil or oceans for use by autotrophs. This starts a whole new food chain.

Food Chains
Different habitats and ecosystems provide many possible food chains that make up a food web.

In one marine food chain, single-celled organisms called phytoplankton provide food for tiny shrimp called krill. Krill provide the main food source for the blue whale, an animal on the third trophic level.

In a grassland ecosystem, a grasshopper might eat grass, a producer. The grasshopper might get eaten by a rat, which in turn is consumed by a snake. Finally, a hawk-an apex predator-swoops down and snatches up the snake.

In a pond, the autotroph might be algae. A mosquito larva eats the algae, and then perhaps a dragonfly larva eats the young mosquito. The dragonfly larva becomes food for a fish, which provides a tasty meal for a raccoon.

Fast Fact

Carnivorous ... Plants?
Most plants on Earth take energy from the sun and nutrients from the soil. A few plants, however, get their nutrients from animals. These carnivorous plants include pitcher plants, Venus flytraps ( Dionaea muscipula), and bladderworts. These plants attract and trap prey, usually insects, and then break them down with digestive enzymes.

Fast Fact

Links in the Chain
Organisms consume nutrients from a variety of different sources in the food chain.

Media Credits

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Illustrators

Mary Crooks, National Geographic Society

Editors

Jeannie Evers, Emdash Editing, Emdash Editing

Producer

National Geographic Society

other

Last Updated

October 19, 2023

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The food chain describes who eats whom in the wild.

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What is a food chain?